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An overview of how Node.JS works

An overview of how Node.JS works

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  • 1.  Interpreted using Google’s V8 JavaScript engine (same one they use in Chrome) Provides some core libraries (network, IO, console, etc.) Supports extensions / modules Is both a runtime environment and a library
  • 2.  It’s not browser / document JavaScript It’s not jQuery It’s not PHP/Ruby/ASP.NET/other server-side language It’s not Apache / IIS
  • 3.  Functions are Objects ◦ Passed as arguments into other functions ◦ Similar to Lambdas / Anonymous Methods in .NET ◦ Ajax.oncomplete = function(result) { document.write(result); }; ◦ $.ajax(function(result) { document.write(result); }); Callbacks EVERYWHERE
  • 4. Wait for Connection
  • 5.  Waiting for expensive operations is stupid Single thread event loop ◦ Your code is single-threaded, so you don’t have to deal with any concurrency / shared state / other multi-threaded problems ◦ Expensive “back-end” operations are spawned as separate processes and trigger events and/or call back to your code when they’re finished
  • 6. “Everything runs in parallel, except your code” Go read this file Go listen for this message Go download this image K, I’m done Waiting
  • 7.  (Almost) All interaction is done via events and callbacks If your code relies on multiple async operations to complete, you’ll have to do a bit of call management / abstraction All of “your code” should return very quickly, or create itself as an async object (via EventEmitter)
  • 8.  “parallel” IO execution allows you to make expensive queries at the same time, increasing efficiency One language to rule them all – server side and client side code for the same web app V8 is one of the fastest script interpreters on the planet Ridiculously fast benchmarks ◦ 600% faster than apache
  • 9. 100,000 requests1,000 concurrent Node Apache / PHPFailed Requests 147 879Requests/seco 4725.4 823.38nd 3Total 211.62 1214.51ms/request 1 0Processing time 40 565(ms)/requestTotal time (s) 21.162 121.451
  • 10.  Uses more CPU and RAM on server (only a little more, but more nonetheless) Can get complicated if doing more than one async call per request Lots of node-specific language constructs ◦ require, exports, etc. Uses JavaScript, which in itself has a lot of quirks and fallacies
  • 11.  Orona